As for an electrostatic high-voltage generator in which an electrostatic charge is transported mechanically and accumulate in a high voltage electrode for obtianing a high voltage, there has been known, for instance, a pellet chain type high-voltage generator, a disc type high voltage generator or the like.
A principle of the pellet chain type high voltage generator is such that, as shown in FIG. 4, a large number of conductive pellets 1 and insulating members 2 are connected together alternatively and flexibly to form a charge carrier unit 3 of a pellet chain, so that if the charge carrier unit 3 is moved between a ground side pulley 4 and a high-voltage side pulley 5, and a negative voltage is applied to a ground side inductor 6 from an electric source 7, a positive electric charge is induced electrostatically to each conductive pellet 1, while a negative electric charge is repelled to escape to the ground side pulley 4, and thus positive electric charge remains at each pellet 1 and is carried from the low-voltage side pulley 4 towards a high voltage electrode 8 and is accumulated therein to result in a high voltage.
In addition, similarly, a negative electric charge is given to each pellet 1 of the charge carrier chain 3 from a high-voltage side inductor 9 associated with the high-voltage electrode 8 and is carried to the ground side pulley 4, and thus by reciprocating the charge carrier unit 3 between the ground side pulley 4 and the high voltage side pulley 5, so that there can be carried doubled electric charges.
A principle of the disc type high-voltage generator is such that, as shown in FIG. 5, a charge carrier unit 3 is constructed into such a disk type one that conductive pellets 1 are disposed along on a circumferential edge of a rotary insulating disc 10, so that in the course of turning of the insulating disc 10, a positive electric charge is given to each pellet 1 from a conductive pulley 12 of a ground side inductor 11, and this positive electric charge carried by each pellet 1 is received by a conductive pulley 14 of a high-voltage side inductor 13 and is accumulated in a high-voltage electrode 8 to result in a high voltage.
In addition, a negative electric charge is given to each pellet 1 from a conductive pulley 16 of another high-voltage side inductor 15 in the high-voltage electrode 8, and is received by a conductive pulley 18 of a ground side inductor 17 provided on the ground side, and thus by one round of the insulation disc 10 of the charge carrier unit 3 between the ground side inductors 11 and 17, there can be carried doubled electric charges.
The pellet chain type and the disc type high-voltage generators shown principally in FIGS. 4 and 5 are so arranged as to be accommodated in respective containers each of which is filled with a SF.sub.6 insulation gas of 7 kg/cm.sup.2 in pressure, and the highest potential gradient in the direction of carrying the charge is 2 Mv/m, in the SF.sub.6 insulation gas of the pressure of 7 kg/cm.sup.2. This highest potential gradient of 2 Mv/m is regulated by the shape, the size and the number of the disposed conductive pellets 1, the insulating resistance force of the insulating members 2 and that of the insulation disc 10 in FIGS. 4 and 5.
Accordingly, in order to obtain a higher voltage in the pellet chain type and the disc type high voltage generators, there is no means other than heightening the insulating gas pressure, elongating the distance in the charge carrying direction of the chain or enlarging the diameter of the insulation disc in FIGS. 4 and 5.
However, in any of the types of high-voltage generators, the mechanism thereof are accommodated in the pressure container of the SF.sub.6 insulating gas in order to obtain a small-sized one as a whole, so that, if the gas pressure is heightened, the maintenance of the insulating gas and the constructional design of the pressure container become difficult.
The increase in the carrying distance of the chain and the diameter of the insulating disc involves an increase in installation area, which is not always considered as an economical design.